Truss-bridge



QN@ Model.) I. A. SPRAGUE.

i TRUSS BRIDGE. No. 287,974. Patented Nov. e, 1883,..

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yTRUSS-BRlDGE.

SPECIFICATION forming part of Letters Patent No. 287,974, dated November 6, 1883.

Application tiled April 14, 1882. (No model.)

duce an arch for bridge-trusses of metal tubes bent to the curve of thearch, the chords being of round or dat bars or wire cables, as may .be preferred. I attain my objects by the arrangements illustrated in the accompanying drawings, in which- Figure l is a side view of one complete span. Fig. 2 is a top view of the same; Fig. 3 an isometric view of one of the'saddles or supports, and Fig. 4 is a view of the chordconnection.

Similar letters of reference refer to similar parts in all the drawings:

A, Fig. 1, is` a tube of metal, preferably iron or steel, of any desired dimensions, bent to the curve of the required arch, and forming an are of a circle of any given radius. The ends of these tubes have screw-threads cut upon them, and are fitted with suitable nuts for the purpose of adjustment and equalization of strains when in place.

E E are angleblgocks placed on suitable abutments.

C represents thechords, which pass through the angle-blocks, and which are secured at the outer ends by screws and nuts. The chords i carry the timbers for the roadway. The saddle-plates may be made in any desired manner, of wrought 0r cast iron, steel, or plateiron. A style of saddle that will probably be found satisfactory in practice is represented inv Fig. 8. It is intended to be made ofcast-iron, and of sufficient strength to bear the strains of compression and stay rods, as

well as the suspension-rods carrying the needle-beams. The bevel portions intended for y the reception of the angular stay-rods are to have a face perpendicular to the axis of said rods, in order to form a goed seat for the nuts holding said rods.

G G are stay-rods, tted with screws and nuts on their upper ends for the purpose of adjustment and equalization, the lower ends being securely bolted to and held by clamps K K, attached to members ofthe chord, as shown in the drawings, the couplings in the chord are to be made at any point required.

A mode of making these couplings is shown at Fig. 4cv which in practice will be' found perfectly satisfactory. It will be seen that the splice is made by a hook on the end of each of two bars, a flat piece of metal, L, be-f ing inserted between the ends, the whole beving'bolted securely together, as shown. 'Ihe block L is of sufficient width to pass above the edge of .the chords, and to allow stay-rods MM. and brace N to be securely bolted to it. At each splice in the chord, stay-rods and braces are always inserted.

From the foregoing and from the drawings it will be seen that my bridge consists of arched tubular 'trusses securely guarded by braces, stay-rods, chord and angle-plates, all iitted with nuts and screws for ready adjustment and easy equalization of strains, and at the saine time securely guarded against lateral or vibratory movements, lwhile the sadydles or supports on the topcf the arches are prevented from displacement by I U -shaped bolts passing round each arch and up through' the saddle, where they are secured by screws and nuts.' as shown in the drawings.

That I claim as my invention, and wish to secure by Letters Patent, is-n A truss-girder for bridges, made of two or more metal tubes bent to the curve of the arch required, said tubes or arcs having their ends -2 t eenen/i J tapped for the reception of nuts for the pur- This speeiieation signed and witnessed this -pose of adjustment, as stated, chords for the 25th day of April, 1881. y

same being formed of rods, bars, or Wire cables, the two former being` coupled at such IRA A. SPRAGUE. 5 points as may be required, in the manner i11ustrated in Fig. 4 or its equivalent, the ends se- Witnesses: cured by nuts and .screws to suitable angle.- ALEX. TIPTON, 1 blocks, as fully described and shown. E. B. WOODRUFF. 

